Needle-free intradermal injection device

ABSTRACT

A needle-free injection device suitable for delivering a therapeutic substance into the intradermal space of a patient. The needle-free injection device includes an injector body defining a syringe end. The device also includes a first handle attached with a hinge to the injector body such that the first handle pivots between an open and a closed position and remains attached to the injector body during an injection, a main spring positioned within the injector body, a return sleeve engaged with the main spring, and a first linkage between the first handle and the return sleeve. The first linkage causes the return sleeve to move away from the syringe end of the injector body when the first handle is moved from the open position to the closed position, thereby compressing the main spring. Needle-free injection systems and methods of operating a needle-free injection device are also disclosed.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.15/644,951 filed on Jul. 10, 2017, which is a continuation of U.S.patent application Ser. No. 15/235,797 (now U.S. Pat. No. 9,700,675)filed on Aug. 12, 2016, which is a continuation of U.S. patentapplication Ser. No. 13/711,765 (now U.S. Pat. No. 9,433,735) filed Dec.12, 2012, entitled “Needle-Free Intradermal Injection Device,” whichclaims priority to U.S. Provisional Patent Application No. 61/570,163,filed Dec. 13, 2011, which application is incorporated by referenceherein in its entirety.

CONTRACTUAL ORIGIN

Certain embodiments disclosed herein were made the support of the UnitedStates Government. The United States Government has certain rights inthis invention under Contract No. 200-2010-37152 between the UnitedStates Centers for Disease Control and Prevention and PharmaJet, Inc.

TECHNICAL FIELD

The embodiments disclosed herein relate generally to needle-freeinjection devices and methods of injecting serums, medicine, inoculantsor other injectable fluid into the intradermal space of a human oranimal.

BACKGROUND

The advantages of needle-free injection devices have been recognized forsome time. Some of the advantages of needle-free devices and methodsinclude the absence of a needle which can intimidate a patient and alsopresent a hazard to healthcare workers. In addition, injection using aneedle may increase the risk of cross-contamination between patients.Furthermore, with an injection device that employs a needle there issubstantial risk of needle breakage in the tissue of a human or animalpatient. The injection jet generated by a needle-free device isgenerally smaller in diameter than a hypodermic needle and thus incertain instances a needle-free injection is less painful than aninjection provided by a hypodermic needle device.

Because of these and other advantages of needle-free injection manyvariations of pneumatic, electronic or spring activated needle-freeinjection devices have been designed to provide a single injection, oralternatively a series of injections to one or more patients. Most knownneedle-free injection devices operate by driving the injectable fluidthrough a fine nozzle with a powered piston to create a fine but highpressure jet of fluid that penetrates the skin. Needle-free injectiondevices are not inherently risk free. For example, it is possible ifprecautions are not taken, to cause a laceration as opposed to a properinjection with a needle-free device. In addition, it is critical todesign a needle-free device with safety features substantiallyminimizing the risk of inadvertent triggering or injection.

Safety issues may involve the risk of accidental discharge of aneedle-free device. Safety issue can become acute in association withdevices that have exposed triggers or devices which include a ram orpiston driving mechanism that can extend beyond the housing of theinjector. The risk of using these types of devices is similar to therisks associated with the triggers on firearms. Thus, the inadvertentpressing of an exposed and armed trigger can cause the accidental orpremature firing or triggering of the needle-free injection device.

One class of reliability issue with known needle-free injection devicesinvolves difficulty delivering an entire preselected dosage ofinjectable liquid into the appropriate tissue of a patient. Thissituation can be exacerbated when the dosage is intended to be deliveredshallowly, in the intradermal space for example. Dosage reliabilityissues have a broad spectrum of causes. One significant underlying causeis the difficulty encountered in the creation of a suitable jet orstream of fluid and introduction of this jet into or through the skin ofa patient. Preferably, the jet will be a very fine jet that will impacta section of taught skin with much of the energy of the stream beingused to penetrate the skin. The elasticity and permeability of apatient's skin can however vary with respect to other patients or acrossdifferent locations on a patient's body. Another reliability issueconcerns difficulty encountered efficiently and accurately pre-fillingneedle-free syringes to a selected dosage without significant waste of apotentially very limited supply of injectable fluid.

The embodiments disclosed herein are directed toward overcoming one ormore of the problems discussed above.

SUMMARY

One embodiment disclosed herein is a needle-free injection devicesuitable for delivering a therapeutic substance into the intradermalspace of a patient. The needle-free injection device includes acompressible main spring which can be compressed to place theneedle-free injection device into an armed configuration. In addition,the device includes at least one and possibly two handles which areattached to the needle-free injection device such that the handle orhandles may pivot between an open and a closed position. In addition,the device includes a linkage between one or each of the handles and themain spring. The linkage provides for the mainspring to be compressedinto the armed configuration when the device handle or handles are movedfrom the open to the closed position.

The disclosed embodiments therefore uniquely include one or more handlesattached to the needle-free injection device which provide for thecompression of the main spring. The leverage necessary to compress amain spring which is suitably sized to deliver a needle-free injectionplaces substantial stress on the hinges connecting the handles to thedevice. Therefore, the needle-free injection device may also includepivot hinges having upper and lower pivot studs and spatially separatedradius surfaces. In use, the upper pivot stud is engaged with the upperhandle and the lower pivot stud is engaged with the lower handle. Theseparate radius surfaces mate with a corresponding or matching surfaceon the upper and lower handles and provide additional support to ahandle beyond that provided by the pivot stud. Device longevity andproper functioning is it promoted by providing both pivot studs andradius surfaces to support each handle. Typically, each handle will besupported by left and right pivot studs and left and right radiussurfaces on each side of the device.

Certain embodiments of the needle-free injection device also include asleeve engaged with the handle linkages and the main spring, whichsleeve is caused to move or slide laterally with respect to the portionsof the injection device housing the mainspring when the handle orhandles are moved from the open position to the closed position. In anembodiment having two handles, the handles made generally be referred toas an upper and lower handle and in selected embodiments the upper andlower handle each have at least one linkage between the respectivehandle and the sleeve or main spring.

Disclosed embodiments also include a catch mechanism configured toengage the handles and hold each in the closed position. Furthermore thedevice may include a release button or release mechanism configured torelease the closed handles and allow each handle to move to the openposition. As noted below, safe usage is enhanced if the release buttoncannot under any circumstance also release energy stored in the mainspring.

The needle-free injection device may include an injector tube housingthe main spring and a hammer. During an injection, force stored in themain spring may be released to drive the hammer forward or toward thenozzle end of the syringe. The hammer is thus in contact with theplunger of the needle-free syringe and positioned to transfer energyfrom the main spring to the plunger causing a needle-free injection.

In certain embodiments the injector tube housing the main spring, hammerand associated apparatus can be caused to move laterally away from thefront (syringe) end of the device when pressure is applied to aneedle-free syringe prior to an injection. The syringe itself isattached to the injector tube in use and moves with the main spring,hammer and associated apparatus. As described in detail below, therespective movement between the injector tube and other elements of theneedle-free injection device provides certain specific functional andsafety advantages.

In particular, the needle-free injection device may include a skintensioning spring configured to bias the injector tube toward thesyringe end of the injection device. The disclosed devices will includean actuation button which, when the device is ready to be operated todeliver an injection, will be in mechanical communication with a hammerrelease. The actuation button therefore, in certain carefully controlledcircumstances, causes the device to deliver a needle-free injection.Safe and effective functioning of the device can be enhanced byconfiguring the actuation button such that it cannot engage the hammerrelease unless the injector tube moved to a position fully away from thefront end of the device.

In embodiments including a skin tensioning spring, the rearward movementof the injector tube and associated apparatus prior to injection isimportant for two distinct reasons. First, prior to an injection, thenozzle end of a needle-free syringe is placed against a patient's skinand the needle-free injection device is pressed toward the patient withsufficient force to compress the skin tensioning spring. This action, inconjunction with the specific shape of the nozzle end, causes thepatient's skin to be appropriately tensioned to assure that a suitableinjection is made. In addition, providing an actuation button that doesnot engage the hammer release mechanism unless the injector tube ismoved to a position fully away from the front end of the device assuresthat an injection cannot be delivered in normal use unless the nozzleend of the needle-free syringe is placed against a patient's skin andthe needle-free injection device is pressed forward with sufficientforce properly tension the skin.

The disclosed device embodiments may be implemented with any type orconfiguration of hammer and hammer release apparatus. One representativetype of hammer release includes one or more ball bearings housed withina ball lock which communicates with a notch defined within the exteriorsurface of the hammer. As noted above, the handles of the device may beopened from a latched configuration after use to compress the mainspring by operating a release switch or button. It is important for safeused to assure that the handle release cannot also or inadvertentlyrelease the main spring and hammer. The disclosed embodiments accomplishthis requirement by including a separate hammer release apparatus whichmay only be actuated by the actuation switch and then only when thedevice is properly positioned for the delivery of an injection as notedabove.

Additional safety may be provided by including a retract buttonmechanically linked to the injector tube. The retract button may beconfigured to cause the injector tube to be locked in the forwardposition, toward the syringe end of the device, unless the retractbutton is depressed or otherwise activated. Thus, a user issubstantially prohibited from accidentally placing the device into aninjection configuration since the injector tube cannot be moved awayfrom the syringe end of the device into the injection configurationdescribed above unless the user deliberately and intentionally permitssaid movement by operating the retract button before or while applyingenough pressure to a patient's skin with the nozzle end of the syringeto compress the skin tensioning spring.

Alternative embodiments disclosed herein include a needle-free injectionsystem comprising a needle-free injection device substantially asdescribed above. In addition a system will include at least oneneedle-free syringe. One disclosed needle-free syringe includes asyringe body having a nozzle at one end and a dose setting surfacesubstantially opposite the nozzle. The syringe will also include aplunger body having a leading end, a seal and a hammer surfacesubstantially opposite the leading end. In use, the plunger body isinserted into a dosage space defined with in the syringe such that theleading end of the plunger points toward the syringe nozzle. The dosagespace is defined within the syringe between the nozzle opening and theplunger seal. A needle-free syringe may be sized and configured suchthat the dosage space has a select dosage volume when the plunger bodyis positioned within the syringe body and the dose setting surface andhammer surface of the plunger are coplanar. The needle-free syringe andplunger assembly may be provided to define any suitable dosage volume.For example, a dosage volume of 0.1 ml is suitable for the delivery ofcertain therapeutic substances into the intradermal space.

The needle-free syringe system may optionally further include a handlesubstantially opposite the plunger body, a separable shaft between theplunger body and the handle, and a break line defined in the separableshaft. In this alternative, the break line defines the hammer surface onthe plunger body. In addition, the handle may include a plungerpositioning surface which cooperates with the hammer surface to positionthe plunger body in a needle-free syringe body such that the dosesetting surface and hammer surface are coplanar. The plunger positioningsurface may define a hole providing a clearance for any nub formed inthe hammer surface upon separation of the plunger body from the handleat the break line. Alternatively or in addition to the above, the end ofthe hammer operatively positioned adjacent to the plunger may cause thehammer surface and dose setting surface to become coplanar when asyringe is loaded into the armed device.

Alternative embodiments disclosed herein include methods of operating aneedle-free injection device or system, to arm the device, deliver aninjection or perform other operations. For example the disclosed methodsmay be implemented to deliver an injection into the intradermal space ofa patient. Disclosed methods include providing a needle-free injectiondevice substantially as described above and moving the handle or handlesfrom the open position to the closed position thereby compressing thedevice mainspring from an un-armed to an armed position. The method mayfurther include loading a needle-free syringe into the device andsubsequently releasing energy stored in the mainspring to drive asyringe plunger forward causing an injection.

As noted above, selected embodiments of the disclosed devices includecertain features which promote safe and effective operation.Accordingly, the disclosed methods may include the steps of activating aretract button to unlock an injector tube or similar apparatus, thusallowing the injector tube, syringe and associated apparatus to be movedwith respect to other device elements. The method may further includeapplying force against a patient's skin at the nozzle end of theneedle-free syringe thereby causing the injector tube to move laterallywith respect to the handles or other stationary elements of theinjector. As noted above, this step properly tensions the patient's skinfor an injection and moves the actuation mechanism of the needle-freeinjector into an injection position. Then and only then, an actuationbutton may be activated to release the energy stored in the mainspringto drive the syringe plunger forward causing an injection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a needle-free injectiondevice.

FIG. 2 is a side elevation view of a needle-free injection device in anopen and ready to charge configuration.

FIG. 3 is a side elevation view of a needle-free injection device in theprocess of being charged.

FIG. 4 is a side elevation view of a needle-free injection device in afully charged configuration.

FIG. 5 is a side elevation view of a needle-free injection device in afully charged configuration with a needle-free syringe inserted therein.

FIG. 6 is a side cross sectional view of a needle-free injection devicein an open and ready to charge configuration.

FIG. 7 is a side cross sectional view of a needle-free injection devicein the process of being charged.

FIG. 8 is a side cross sectional view of a needle-free injection devicein a fully charged configuration.

FIG. 9 is a side cross sectional view of a needle-free injection devicein a fully charged configuration with a needle-free syringe insertedtherein, after compression of a skin tensioning spring immediately priorto an injection.

FIG. 10 is a side cross sectional view of a needle-free injection deviceafter an injection.

FIG. 11 is a side cross sectional view of selected internal structuresof a needle-free injection device, prior to unlocking the injector tubewith the retract button.

FIG. 12 is a perspective cross sectional view of selected internalstructures of a needle-free injection device, prior to arming the devicefor an injection.

FIG. 13 is a perspective cross sectional view of selected internalstructures of a needle-free injection device, after the main spring hasbeen compressed and locked, but before the compression of the skintensioning spring.

FIG. 14 is a side cross sectional view of selected internal structuresof a needle-free injection device after compression of a skin tensioningspring immediately prior to an injection.

FIG. 15 is a perspective view of a pivot plate.

FIG. 16A is an exploded perspective view of a syringe, handle andplunger system.

FIG. 16B is a perspective view of the syringe, handle and plungersystem.

FIG. 16C is an exploded side elevation view of the syringe, handle andplunger system.

FIG. 17A is a perspective view of a needle-free syringe.

FIG. 17B is a front (nozzle end) view of the needle-free syringe.

FIG. 17C is a side elevation view of the needle-free syringe.

FIG. 18 is a flow chart representation of a method of delivering aneedle-free injection.

DETAILED DESCRIPTION

Unless otherwise indicated, all numbers expressing quantities ofingredients, dimensions reaction conditions and so forth used in thespecification and claims are to be understood as being modified in allinstances by the term “about”.

In this application and the claims, the use of the singular includes theplural unless specifically stated otherwise. In addition, use of “or”means “and/or” unless stated otherwise. Moreover, the use of the term“including”, as well as other forms, such as “includes” and “included”,is not limiting. Also, terms such as “element” or “component” encompassboth elements and components comprising one unit and elements andcomponents that comprise more than one unit unless specifically statedotherwise.

FIG. 1 is an exploded perspective view of a needle-free injection device10. The needle-free injection device 10 includes an injection powersource, in particular, a main spring 12 which may be compressed to storeenergy for subsequent release to power an injection. The main spring 12is engaged with a hammer 14 such that when energy stored within the mainspring 12 is released, the hammer 14 is driven toward and into contactwith the plunger of a needle-free syringe providing for a needle-freeinjection as described in detail below. The main spring 12, hammer 14and associated apparatus may be housed within an injector tube 16.

The needle-free injection device 10 also includes a core 18 which mayalternatively be referred to as the injector device body. The core 18may include, but is not limited to a pivot sleeve 20. The needle-freeinjection device 10 also includes a return sleeve 22, syringe receptacle24 and latch and release sleeve 26. The structure and functioning ofeach of these elements is described in detail below.

It may also be noted from FIG. 1 that the needle-free injection device10 includes at least one handle, and in the illustrated embodiment, twohandles, which may be referred to as an upper handle 28 and lower handle30. In the illustrated embodiment the handles 28, 30 are attached to thepivot sleeve 20. At least one handle associated with the injector deviceor alternatively both the upper handle 28 and lower handle 30 may bemoved from an open position to a closed position by a user to providethe force necessary to compress, store energy and thereby arm the mainspring 12 for an injection.

Also shown on FIG. 1 are three control buttons or switches associatedwith the device including an actuation button 32, retract button 34 andrelease button 36. Other operational buttons could be provided inalternative embodiments.

FIGS. 2-5 show external side elevation views of the needle-freeinjection device 10 with the handles 28, 30 and other elements invarious operational states. In particular, FIG. 2 shows the handles 28,30 in the fully open position. In the FIG. 2 position the main spring 12is extended or de-compressed and ready to be charged for an injection.FIG. 3 illustrates the handles 28, 30 in a partially closedconfiguration, for example as the handles would be positioned during theprocess of compressing the main spring 12, but prior to fullcompression. FIG. 4 shows the handles 28, 30 fully closed and latched.In the FIG. 4 configuration the main spring 12 is fully charged andready to provide for an injection as described in detail below. FIG. 5illustrates the charged needle-free injection device 10 with aneedle-free syringe 40 inserted into the syringe receptacle 24 at thesyringe end 38 of the needle-free injection device 10.

FIGS. 6-14 show various cross-sectional views of the needle-freeinjection device 10 in selected operational states. FIGS. 6-14 may thusbe referred to in order to more fully understand the elements andoperational subsystems providing enhanced convenience, safety,durability, and effectiveness to the user of a needle-free injectiondevice 10. In particular, FIG. 6 is a cross-sectional view of theneedle-free injection device 10 with the handles 28, 30 in a fully openposition. As noted above, in the FIG. 2 or FIG. 6 position, the mainspring 12 is in a decompressed and ready to charge state. As may beobserved on FIG. 6, each of the handles 28, 30 engages with a linkage42, 44 respectively which in turn is engaged with the return sleeve 22.In the embodiment illustrated in FIG. 6, the upper handle 28 is engagedwith an upper linkage 42 and the lower handle 30 is engaged with a lowerlinkage 44. Both the upper and lower linkage 42, 44 have a bearingsurface which engages a corresponding surface on the return sleeve 22.As may be noted by comparing FIG. 6 with FIG. 7 (which shows the handles28, 30 in a partially closed position) as the handles 28, 30 are closed,the linkages 42, 44 force the return sleeve 22 away from the syringe end38 of the device. As the return sleeve 22 is forced toward the rear ofthe device by the handles 28, 30 and linkages 42, 44, the main spring 12is compressed. FIG. 7 shows the main spring 12 in a partially compressedstate, FIG. 8 shows the main spring 12 in a fully compressed state. Itis important to note that the particular configuration of handles,linkages, a return sleeve and main spring illustrated in the figures isnot limiting. Other mechanical configurations could be used to implementthe functionality of handle closure acting to compress the main springand charging an alternative embodiment of needle-free injection device.

Returning to FIG. 6, it may be noted that the latch and release sleeve26 includes an upper latching member 46 and a lower latching member 48.Each handle 28, 30 has a corresponding latching surface with the upperhandle 28 having an upper latching surface 50 and the lower handle 30having a lower latching surface 52. In use, the upper latching member 46engages the upper latching surface 50 when the handles 28, 30 are in afully closed position. The lower latching member 48 and lower latchingsurface 52 engage in the same way. Thus, when the handles 28, 30 areclosed to the fully closed configuration illustrated in FIG. 8, thehandles 28, 30 are latched shut. The handles 28, 30 when placed in theFIG. 8 closed position are configured to remain latched shut until suchtime as the release button 36 is depressed, moving the latch and releasesleeve 26 forward a short distance with respect to the injector tube 16which causes the latch members 46, 48 and latch surfaces 50, 52 todisengage returning the needle-free injection device 10 to the FIG. 6configuration. As will be described below, the release button 36 cannotoperate to release the main spring 12 under any circumstance providingused safety.

It may also be noted by comparison of FIGS. 6, 7 and 8 that as thereturn sleeve 22 is moved away from the syringe end 38 of theneedle-free injection device 10, one or more return springs 54 areextended. Return spring extension biases the return sleeve 22 toward thesyringe end 38 of the needle-free injection device 10 such that thereturn sleeve 22 is motivated to slide forward when the handles 28, 30are opened.

FIGS. 11 and 12 are side elevation and perspective cross-sectional viewsof the needle-free injection device 10 in the handle open/ready tocharge position of FIG. 6. FIGS. 13 and 14 are perspective and frontelevation cross sectional views of needle-free injection device 10 afterthe main spring has been compressed (FIG. 13) and after a skintensioning spring has also been compressed, as described in detail below(FIG. 14). In the FIG. 11-14 views, the handles 28, 30 and various otherstructures have been removed to provide a more detailed view of thereturn sleeve 22, main spring 12, hammer 14 and associated apparatus. Inparticular, FIG. 12 shows the engagement of the upper linkage 42 andlower linkage 44 with corresponding surfaces on the return sleeve 22such that closing the handles 28, 30 causes the linkages 42, 44 to forcethe return sleeve 22 and hammer away from the syringe end 38 of theneedle-free injection device 10 thereby compressing the main spring 12.

As also shown in the FIG. 12 view, side posts 55 extend from the portionof the hammer 14 adjacent the main spring 12. The side posts could beindependent structures, or as shown in FIG. 1 a pin extending throughthe hammer. The side posts 55 are engaged with clips 56 when the returnsleeve is retracted. Thus, the clips 56 bind the hammer 14 to the returnsleeve 22 when the needle-free injection device 10 is in an open andready to charge configuration and as the device is charged. As bestshown in FIG. 13, as the needle-free injection device 10 nears andreaches the fully charged position, a hammer release 57 including ballbearings 60 associated with a ball lock sleeve 58 drop into a notch 62defined in the hammer. Thus, the ball lock sleeve 58 and associatedapparatus lock the hammer 14 in a charged position at a time when theclips 56 are still engaged with the side posts 55. When the handles 28,30 are fully closed, the clips 56 move into engagement with the rampedfront surface 64 of the return sleeve to be forced away from the sideposts 55 and therefore to allow for subsequent clearance between theside posts and the return sleeve as the device is fired.

As is best shown in FIGS. 5, 8 and 9, when the needle-free injectiondevice 10 is placed in a fully charged configuration and the handles 28,30 are locked; a needle-free syringe 40 may be placed into the syringereceptacle 24. As described in detail below, the needle-free injectiondevice 10 includes various safety systems to assure that an inadvertentinjection is not made when the needle-free syringe 40 is placed into thesyringe receptacle 24 or at any other time.

In particular, it may be noted by comparing FIG. 8 with FIG. 9 that thecombined elements of the syringe receptacle 24, a needle-free syringe40, the hammer 14, main spring 12 and ball lock sleeve 60 may all bemoved, in association with the injector tube 16 housing the main springand hammer, laterally away from the syringe end of the pivot sleeve 20and associated handles. A skin tensioning spring 66 is provided whichbiases against the lateral rearward movement of the injector tube 16.See for example FIG. 11 where the skin tensioning spring 66 is notcompressed and FIG. 14 where the skin tensioning spring 66 has beencompressed. The rearward movement of the injector syringe receptacle 24,needle-free syringe 40, hammer 14, main spring 12 and ball lock sleeve60 is important for two distinct reasons. First, prior to an injection,the nozzle end 68 of a needle-free syringe 40 is placed against apatient's skin and the needle-free injection device 10 is pressed towardthe patient with sufficient force to compress the skin tensioning spring66. This action, in conjunction with the specific shape of the nozzleend 68, causes the patient's skin to be appropriately tensioned toassure that a suitable injection is made. It may be noted from acomparison of FIG. 8 and FIG. 9 or FIG. 11 with FIG. 14 that both theforward end 70 of the syringe receptacle 24 and the rear end 72 of theinjector tube 16 slide backward (away from the syringe end 38 of thedevice) with respect to other elements of the needle-free injectiondevice 10 as the skin tensioning spring is compressed. Thisfunctionality provides for proper skin tensioning as described above andalso is linked to device safety as described below.

The needle-free injection device 10 is provided with an actuation button32 which in certain instances releases the main spring to provide aninjection. As shown in FIG. 9 and FIG. 14, when the needle-freeinjection device 10 is fully armed, the skin tensioning spring 66 isfully compressed and the injector tube and the elements within orattached to the injector tube are moved or slid fully away from thesyringe end of the device as described above, the actuation button 32communicates with the ball lock sleeve 58 through activation linkage 74.As shown in FIG. 10, when the actuation button 32 is depressed in thisfully charged and armed configuration, the activation linkage 74 forcesthe ball lock sleeve 60 toward the rear of the device a short distancefreeing the ball bearings 60 from the notch 62 allowing the main spring12 to rapidly decompress, forcing the hammer 14 into contact with theplunger 76 of the needle-free syringe 40. As shown in FIGS. 6 and 7,however, the activation linkage 74 is not positioned in physicalcommunication with the actuation button 32 until such time as theinjector tube 16 and associated apparatus have been moved fully towardthe rear of the needle-free injection device 10 by skin tensioningpressure on the nozzle end 68 of the needle-free syringe 40. Thus, theneedle-free injection device 10 cannot be activated and an injectioncannot be delivered in normal use unless the nozzle end 68 of theneedle-free syringe 40 is placed against a patient's skin and theneedle-free injection device 10 is pressed forward with sufficient forceto compress the skin tensioning spring 66 and thereby properly tensionthe skin.

Additional safety is provided by the retract button 34 and associatedapparatus. As is most readily seen in FIGS. 11 and 14, the retractbutton 34 communicates with a safety collar 78 having a notch 80 definedtherein. The notch 80 corresponds with a tab 82 extending from anexterior surface of the syringe receptacle 24. As noted above, thesyringe receptacle 24, injector tube 16, hammer 14 and syringe 40 mayall be made to collectively slide or otherwise move toward the rear ofthe needle-free injection device 10 when appropriate skin tension isapplied to the nozzle end 68 of the syringe 40. The tab 82 interfereswith the safety collar 78 preventing rearward motion of the aboveassemblies until such time as the retract button 34 is depressed. Thus,in normal use, even though the main spring may be compressed, the devicecannot be placed into a firing or injection-enabled configurationwithout first depressing the retract button 34. As noted above, theactuation button 32 cannot be engaged with the ball lock sleeve 60 untilthe injector tube 16 has been moved into a firing or injectionconfiguration. Accordingly, a very high degree of safety is provided bythe cooperation of the retract button 34 and actuation button 32 andassociated assemblies. The device can not be accidentally placed into afiring position because of the retract button and the device can not befired until it is intentionally placed into a firing position.

In certain embodiments the handles 28, 30 are fabricated from a plasticor other injection molded material. The handles 28, 30 experiencesubstantial force when closed to compress the main spring 12 and chargethe needle-free injection device 10. Accordingly, effective needle-freeinjection device 10 operation and longevity may be enhanced by providinga hinge which more fully supports handle pivot operation when comparedto traditional pivot pins. FIG. 15 is a detailed perspective view of apivot plate 84, one of which is located on each side of the device tosupport and provide for suitable pivoting of the upper and lowerhandles. Each pivot plate 84 includes an upper pivot stud 86 and lowerpivot stud 88 which receive and support corresponding holes in the upperand lower handles 28, 30 providing for pivoted handle articulation. Thepivot plates 84 also include upper and lower radius surfaces 90, 92,respectively. The upper and lower radius surfaces 90, 92 are configuredto mate with a corresponding surface on the inside of each handle 28, 30to provide support to the handle as it is move from an open to a closedposition. Together, the pivot studs 86, 88 and upper and lower radiussurfaces 90, 92 provide each handle 28, 30 with significantly enhancedsupport when compared to a simple pivot pin type attachments.

FIGS. 16A-16C include several views of a needle-free syringe 40 andsyringe plunger system 94 showing certain enhancements. In particular,the needle-free syringe 40 may include at least two raised surfaces 96defining at least one orientation channel 98 on the body of theneedle-free syringe, typically at the trailing end. The orientationchannel 98 is sized and configured to engage with corresponding syringeorientation guides associated with the syringe receptacle 24. Thus, auser may install a needle-free syringe 40 by sliding one or moreorientation channels 98 over corresponding orientation guides until thepawls or another engagement mechanism engage with the syringe.Therefore, a syringe may be installed and locked for use withoutrequiring the syringe body to be twisted as is necessary withconventional bayonet or screw type syringe mounts. The needle-freesyringe 40 may also include visual indicia 100 which are illustrated assmall raised portions but which could be implemented with any visuallyobservable marker. In use, the visual indicia are placed in a visuallyidentifiable position relative to or concealed by the forward end 70 ofthe syringe receptacle 24 thereby providing visual confirmation that asyringe 40 is properly installed.

It may be convenient to remotely prepare multiple needle-free syringes40 for use with the needle-free injection device 10. For example, oneoperator could be loading needle-free syringes with an injectable fluidwhile another operator installs the needle-free syringes into the deviceand performs injections. Remote filling to a proper pre-determineddosage is facilitated by providing a plunger system 94 which includes aplunger body 76 and a seal 99 (See FIGS. 16A and 16C) sized to fit influid-tight engagement with the interior chamber of the syringe, therebydefining a fluid receiving dosage space within the needle-free syringe40. As shown in FIG. 16, the plunger system 94 also may include a handle102. The handle 102 may be conveniently separated from the plunger body76 at a break line 104 defined in a separable shaft 103 between theplunger body and handle. In use the handle 102 and separable shaft 103are typically broken away from the plunger body at the break line 104after the syringe is filled, but before it is loaded into a device 10.Upon removal of the handle 102 and separable shaft 103, the trailing endof the plunger body 76 defines a hammer surface 105 which engages withthe hammer 14 during an injection.

As shown in FIG. 9, the interior portion of the syringe 40 defines adosage space 106 within the interior walls of the syringe between thenozzle and the plunger seal 99. This dosage space may be sized andconfigured to have a pre-selected injectable fluid dosage volume whenthe plunger body 76 is positioned within the syringe such that thehammer surface 105 is placed in a pre-defined spatial relationship witha dose setting surface 107 on the trailing edge of the syringe,substantially opposite the nozzle 68 (see FIG. 17A-17C). For example,the dosage space 106 may be sized to have a specific volume, for example0.1 ml, when the hammer surface 105 is coplanar with the dose settingsurface 107.

As shown in FIG. 9, the hammer 14 may be used to automatically positionthe plunger body 76 such that the hammer surface 105 and dose settingsurface 107 are coplanar. For example, the syringe and plunger assemblymay be loaded into the needle-free injection device 10 with the hammersurface 105 extending slightly beyond the dose setting surface 107 andthe location of the corresponding end of the hammer 14 causes these twosurfaces to become coplanar. It may also be noted that the leading edgeof the hammer 14 may include a recess which provides clearance for anyextension or nub remaining beyond the hammer surface 105 when theseparable shaft 103 is removed from the plunger body 76 at the breakline 104.

Proper dose setting may also be accomplished in the absence of theneedle-free injection device 10 by using the plunger positioning surface108 associated with the handle 102 to manually position the hammersurface 105 to be coplanar with the dose setting surface 107. Theplunger positioning surface 108 may, as shown in FIG. 16, include a hole109 which provides clearance for any extension or nub formed in thehammer surface 105 upon separation of the plunger body from the handleat the break line. Thus, during a remote filling operation, a user mayinsert the plunger body 76 and attached handle assembly 95 fully into aneedle-free syringe 40 such that the leading end of the plunger body 76is in contact with the interior surface of the nozzle. The nozzle may beplaced in fluid communication with a supply of injectable material. Thehandle may be then be used to withdraw the plunger body 76 to a pointwhere the hammer surface 105 extends beyond the dose setting surface 107of the syringe, thereby slightly over-filling the syringe. The handleand separable shaft may then be removed at the break line 104 and thehammer surface and dose setting surface 107 made to be coplanar (thusprecisely setting the selected dosage) by pressing upon the hammersurface with the plunger positioning surface 108 of the handle. Theforegoing operation may be performed while the nozzle is continuouslymaintained in sterile fluid communication with an injectable substancesupply, thus minimizing waste.

Returning to FIG. 16 it may be noted that the needle-free syringe 40 maybe provided with a cap 110 sized to engage the nozzle end of the syringebody. FIGS. 17A-17C include several alternative views of a needle-freesyringe 40 as described herein.

Alternative embodiments include methods of charging, operating andfilling a needle-free injector as described above. For example, oneembodiment includes a method of arming a needle-free injection devicecomprising the steps of providing a needle-free injection device orsystem as disclosed above, moving one or more handles associated withthe needle-free injection device from an open position to a closedposition thereby compressing the main spring of the needle-freeinjection device from an un-armed to an armed position. The method mayfurther include actuating a release to cause an injection.

As more particularly shown in the flow chart of FIG. 18, a method 1800may include the steps of moving at least one handle from an open to aclosed position to compress the main spring of injection device (Step1802). Next, a needle-free syringe may be loaded into the injectiondevice (Step 1804). A user may then activate a retract button to unlockan injector tube within the device, allowing the device to be positionedfor an injection (Step 1806). As noted above, the injector cannot befired at this point in time because the firing or injection enablingmechanism is not in mechanical communication with actuation button.Immediately prior to injection, the user may apply force against asubject's skin at the nozzle end of the needle-free syringe, causing theinjector tube to move laterally into an injection firing position. (Step1808). As noted above movement into the firing/injection position may beprohibited unless the retract button has been depressed. Then, with thepatient's skin properly tensioned, the user may activate an actuationbutton to release the energy stored in the main spring to drive thesyringe plunger causing an injection (Step 1810).

Various embodiments of the disclosure could also include permutations ofthe various elements recited in the claims as if each dependent claimwas a multiple dependent claim incorporating the limitations of each ofthe preceding dependent claims as well as the independent claims. Suchpermutations are expressly within the scope of this disclosure.

While the embodiments described herein have been particularly shown anddescribed with reference to a number of possible variations, it would beunderstood by those skilled in the art that changes in the form anddetails may be made to various components or elements without departingfrom the spirit and scope of the embodiments and that the variousembodiments disclosed herein are not intended to act as limitations onthe scope of the claims. All references cited herein are incorporated intheir entirety by reference.

What is claimed is:
 1. A needle-free injection device comprising: aninjector body defining a syringe end of the injector body; a firsthandle attached to the injector body such that the first handle pivotsbetween an open and a closed position and remains attached to theinjector body during an injection; a main spring positioned within theinjector body; a return sleeve positioned outside of the injector bodyand engaged with the main spring; and a first linkage between the firsthandle and the return sleeve, wherein the first linkage causes thereturn sleeve to move away from the syringe end of the injector bodywhen the first handle is moved from the open position to the closedposition, thereby compressing the main spring.
 2. The needle-freeinjection device of claim 1 further comprising a return spring biasingthe return sleeve toward the syringe end of the injector body.
 3. Theneedle-free injection device of claim 1 further comprising: a secondhandle; and a second linkage between the second handle and the returnsleeve.
 4. The needle-free injection device of claim 3 furthercomprising at least one pivot hinge between the injector body and thefirst and second handles, the pivot hinge comprising; two pivot studswith a first pivot stud being engaged with the first handle and a secondpivot stud being engaged with the second handle; and two radius surfaceswith a first radius surface mating with a corresponding surface on thefirst handle and a second radius surface mating with a correspondingsurface on the second handle.
 5. The needle-free injection device ofclaim 3 further comprising a latch and release sleeve to engage thefirst and second handles and hold each handle in the closed position. 6.The needle-free injection device of claim 5 further comprising a releasebutton to release the handles from engagement with the latch and releasesleeve and allow each handle to move to the open position.
 7. Theneedle-free injection device of claim 1 further comprising: a hammerengaged with the main spring; and a hammer release in mechanicalcommunication with an actuation button, wherein actuation of theactuation button when the main spring is compressed can permit the mainspring to decompress, driving the hammer toward the syringe end of theinjector body.
 8. The needle-free injection device of claim 7 whereinthe hammer release comprises one or more ball bearings housed within aball lock.
 9. The needle-free injection device of claim 7 furthercomprising: a side post extending from the hammer; and a clip extendingfrom the return sleeve, wherein the clip binds the side post and thehammer to the return sleeve when the handle is not in a fully closedposition.
 10. The needle-free injection device of claim 9 wherein theclip is disengaged from the side post and the hammer when the handle isin a fully closed position.
 11. A method of operating a needle-freeinjection system comprising: providing a needle-free injection devicecomprising: an injector body defining a syringe end of the injectorbody; a first handle attached to the injector body such that the firsthandle pivots between an open and a closed position and remains attachedto the injector body during an injection; a main spring positionedwithin the injector body; a return sleeve positioned outside of theinjector body and engaged with the main spring; and a first linkagebetween the first handle and the return sleeve; moving the first handlefrom the open position to the closed position causing the first linkageto cause the return sleeve to move away from the syringe end of theinjector body thereby compressing the main spring.
 12. The method ofclaim 11 further comprising: providing a return spring biasing thereturn sleeve toward the syringe end of the injector body; and movingthe handle from the closed position to the open position, permitting thereturn spring to move the return sleeve toward the syringe end of theinjector body.
 13. The method of claim 11 further comprising: providinga second handle attached to the injector body such that the secondhandle pivots between an open and a closed position; providing a secondlinkage between the second handle and the return sleeve; and moving thefirst handle and the second handle from the open position to the closedposition causing the first linkage and the second linkage to cause thereturn sleeve to move away from the syringe end of the injector bodythereby compressing the main spring.
 14. The method of claim 13 furthercomprising: providing at least one pivot hinge between the first handle,the second handle and the pivot hinge, said pivot hinge comprising; twopivot studs with a first pivot stud being engaged with the first handleand a second pivot stud being engaged with the second handle; and tworadius surfaces with a first radius surface mating with a correspondingsurface on the first handle and a second radius surface mating with acorresponding surface on the second handle.
 15. The method of claim 13further comprising: providing a latch and release sleeve; and engagingthe first and second handles with the latch and release sleeve to holdeach handle in the closed position.
 16. The method of claim 15 furthercomprising: providing a release button in mechanical communication withthe latch and release sleeve; and actuating the release button todisengage the handles from the latch and release sleeve and allow eachhandle to move to the open position.
 17. The method of claim 11 furthercomprising: providing a hammer engaged with the main spring; providing ahammer release in mechanical communication with an actuation button; andactuating the actuation button when the main spring is compressed topermit the main spring to decompress, driving the hammer toward thesyringe end of the injector body.
 18. The method of claim 17 wherein thehammer release comprises one or more ball bearings housed within a balllock.
 19. The method of claim 17 further comprising: providing a sidepost extending from the hammer; providing a clip extending from thereturn sleeve; and binding the side post and the hammer to the returnsleeve with the clip when the handle is not in a fully closed position.20. The method of claim 19 further comprising disengaging the clip fromthe side post and the hammer when the handle is in a fully closedposition.